Floating Raised Frame in BAW Resonators for Spurious Mode Suppression
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Solution Overview
Problem
Bulk acoustic wave devices face challenges in achieving a high quality factor (Q) and low Gamma loss, with raised frames often exciting spurious resonances that increase Gamma loss in carrier aggregation bands, affecting multiplexer performance.
Innovation Solution
The implementation of a bulk acoustic wave device with a floating raised frame structure, which is electrically isolated from the electrode and positioned between the electrode and the piezoelectric layer, reduces spurious modes by maintaining a floating potential and using air gaps or insulating materials to minimize lateral energy leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a raised frame structure is used in BAW devices, then lateral energy leakage is reduced and quality factor is improved, but spurious resonances are excited and Gamma loss increases
Solution Approach 1:
A floating raised frame structure is introduced as an intermediary element between the electrode and the piezoelectric layer. This floating frame acts as a mediator that provides mechanical support and reduces lateral energy leakage while maintaining electrical isolation to prevent excitation of spurious resonances. The floating frame is electrically disconnected from the electrode, allowing it to serve its structural function without generating harmful spurious modes.
2Strength
If the raised frame is electrically connected to the electrode, then structural support is provided, but spurious modes are excited due to electrical coupling
Solution Approach 1:
The raised frame structure is segmented into two functionally distinct parts: a floating raised frame portion that provides structural support without electrical connection, and an electrode portion that handles electrical signaling. This segmentation allows the structural and electrical functions to be decoupled, enabling the frame to provide mechanical strength while avoiding electrical coupling that would excite spurious modes.
Solution Approach 2:
The floating raised frame serves as a structural intermediary between the substrate and the electrode assembly. It provides mechanical support and defines the active region boundaries without being electrically connected to the electrode, thus mediating the structural requirements while preventing electrical coupling that would lead to spurious mode excitation.
3Productivity
If carrier aggregation bands are used to increase bandwidth, then communication capacity is improved, but Gamma loss increases due to spurious resonances
Solution Approach 1:
The floating raised frame structure acts as an intermediary that enables the use of carrier aggregation bands by suppressing spurious resonances. By providing structural support without electrical connection, it allows broader frequency ranges to be used for carrier aggregation while maintaining low Gamma loss, thus enabling increased bandwidth utilization without the penalty of spurious mode-induced energy loss.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances the quality factor (Q) and reduces Gamma loss, leading to improved multiplexer performance by suppressing spurious modes and maintaining electromechanical coupling efficiency.
Implementation Method 1
In BAW resonators, acoustic waves propagate in a bulk of a piezoelectric layer
Implementation Method 2
a piezoelectric layer positioned between the first electrode and the second electrode
Data Source
AI summary
Aspects of this disclosure relate to a bulk acoustic wave device with a floating raised frame structure. The bulk acoustic wave device includes a first electrode, a second electrode, a piezoelectric layer positioned between the first electrode and the second electrode, and a floating raised frame structure positioned on a same side of the piezoelectric layer as the first electrode and spaced apart from the first electrode. The floating raised frame structure is at a floating potential. The bulk acoustic wave device can suppress a raised frame mode. Related methods, filters, multiplexers, radio frequency front ends, radio frequency modules, and wireless communication devices are disclosed.